Sheets of resinous composition have found widespread use as a decorative and wear resistant coverings for a wide range of products. Such sheets are used, for example, as wall, floor and table coverings. When these sheet materials are made with chips or other particulate material, they are commonly referred to as inlaids. Inlaid floor coverings are normally characterized as those which maintain their decorative appearance as the surface is worn or abraded away. The patterns and designs and other decorative effects of these inlaid coverings are of prime importance in insuring commercial acceptability in the public market.
Modern inlaids generally fall into two classifications: resilient and non-resilient. Resilient inlaids include a substantially continuous layer of foam and are usually made by incorporating solid particulate material into a plastisol coating, followed by gelling and fusing. Non-resilient inlaids do not contain a foam layer and are usually made by sintering and/or calendering, or otherwise particulate material compacting.
Many processes are known for embedding various particles into a clear plastisol in order to make decorative inlaid patterns. Examples of these processes are found in U.S. Pat. No. 4,440,826 (Armstrong World Industries), U.S. Pat. No. 4,212,691 (Congoleum Corp.), U.S. Pat. No. 4,794,020 (Tarkett Inc.), U.S. Pat. No. 4,675,216 (Sommer S. A.) and U.S. copending application Ser. No. 553,319, filed Jul. 17, 1990, now U.S. Pat. No. 5,071,680. Metallic or pearled flakes have also been used to replace grounded PVC sheets. Some people have also combined all these different techniques to create original decorations.
Some of these processes involve the deposition of particles of colored polyvinylchloride (PVC) having a high carbonate or vinyl concentration. Others are arranged to create geometric structures. The deposits constitute the surface layer of all the sheet materials produced by these processes and the desired sheet is completed by applying clear plastisol, either translucent or opaque, which serves as a binding agent between the particles. (see U.S. Pat. No. 4,916,007 Tarkett Inc.)
The additional decorative benefit of birefringent particles added to inlaid sheet materials as described above is also an object of the present application.